Outdoors

Sturgeon research ongoing in Penobscot

Four years ago, Keith Bates caught the attention of University of Maine researchers and federal fisheries officials when he hooked, landed and released a fish that many didn’t even know still existed in the Penobscot River.

Now, four years later, UMaine’s resulting research project is turning up some valuable information about that species — shortnose sturgeon — and raising plenty of questions that have yet to be answered.

A year ago, Gayle Zydlewski, a professor in the school of marine sciences at UMaine, said that the random sturgeon landing by a fisherman targeting striped bass from a riverside park in South Brewer put several wheels in motion.

“That kind of prompted us to say, ‘Well, gee, we need to do a really detailed study to find out what’s out there,” Zydlewski said during an interview last summer.

Story continues below advertisement.

Much of that research was carried out by graduate student Stephen Fernandes as he earned his masters degree.

This year, his colleague, graduate student Phil Dionne, has continued working on the sturgeon study that he expects to continue long after he finishes his masters degree.

Shortnose sturgeon, which can reach lengths of about five feet, along with much larger Atlantic sturgeon, which can reach 18 feet long and nearly 1,000 pounds, are the subject of the study.

At the recent Penobscot River Revival, Dionne took time out to talk with Dave Simpson of ABC-7 for a “Going Outdoors” segment that Simpson and I produce together.

Dionne told Simpson that researchers have learned that the bottom-dwelling shortnose sturgeon are moving around a lot more than they had anticipated.

“We’ve documented them in the St. George and the Damariscotta and the Medomak [rivers], in addition to the Penobscot and the Kennebec rivers,” Dionne said. “This year we have an additional receiver in the Passagassawaukeag River as well, to see if they’re moving through there. It’s something neat and interesting. It’s something that we’ve never really seen anyplace else before, these large movements between different river systems that are so far apart.”

The fish that are captured in the Penobscot are fitted with an acoustic tag that can be read by receivers in several Maine rivers. If they pass a receiver in the Penobscot, researchers find out about it. And if they move into another river that’s equipped with the receivers, researchers learn where they’re going, and at what times of year they’re going there.

“They’re regularly moving back and forth. It seems like there’s a couple times during the year that they’re moving more frequently, but it seems like they’re moving pretty readily between these systems,” Dionne said.

And it’s not just a few fish that are showing the urge to move from river to river, Dionne said.

About 25 percent of those fish that have been caught in the Penobscot and acoustically tagged have been tracked in other rivers, he said.

“We don’t know why [they’re moving], and that’s part of the project as well,” Dionne said. “We are trying to document spawning to find out if the sturgeon are spawning in the Penobscot River. We know that they do spawn in the Kennebec and the Androscoggin, but we are uncertain about the Penobscot, so we don’t know if the population here is coming from the Kennebec and just foraging here or if it’s an actual separate population and they just seem to move back and forth.”

That movement between river systems makes one of the project’s goals — determining a population estimate — a tricky proposition.

“What I’m trying to do is to establish a population estimate during periods of the year in the Bangor region, and using different techniques we have population estimates ranging from about 400 to about 2,000,” Dionne said.

And as the research has progressed, Dionne and others have learned that fish gather into sizeable groups at certain times of year.

“This past winter we went out with some acoustic sonar to actually visualize the fish in their wintering area, where they congregate very tightly, and some of our estimates in that area were as many as 800 fish in a very small area,” Dionne said.

That area isn’t far from downtown Bangor, but in true fisherman fashion, that’s as precise a location as I’ll give.

The reason for that is simple: The sturgeon ought to be left alone by all of us who aren’t trained researchers.

Last summer Zydlewski cautioned anglers to remember a few important facts about sturgeon: They are endangered. Don’t try to catch them. And if you do inadvertently catch one, release it as quickly and gently as possible.

That warning still holds.

Having sturgeon in the Penobscot, and having the river as the site of ongoing research, is great news indeed.

It’s fine to look forward to future updates about the sturgeon population, and to take an interest in the rare fish.

But the best thing anglers can do is to take all the steps we can to avoid harassing the fish.